Control.Monad.Trans.List

The ListT monad transformer, adding backtracking to a given monad, which must be commutative.

The ListT monad transformer

newtype ListT m a

Parameterizable list monad, with an inner monad.

Note: this does not yield a monad unless the argument monad is commutative.

Constructors

ListT (m [a])

Instances

MonadTrans ListT

Monad m => Monad (ListT m)

Functor m => Functor (ListT m)

Monad m => MonadPlus (ListT m)

Applicative m => Applicative (ListT m)

Foldable f => Foldable (ListT f)

Traversable f => Traversable (ListT f)

Applicative m => Alternative (ListT m)

MonadIO m => MonadIO (ListT m)

Show1 m => Show1 (ListT m)

Read1 m => Read1 (ListT m)

Ord1 m => Ord1 (ListT m)

Eq1 m => Eq1 (ListT m)

(Eq1 m, Eq a) => Eq (ListT m a)

(Ord1 m, Ord a) => Ord (ListT m a)

(Read1 m, Read a) => Read (ListT m a)

(Show1 m, Show a) => Show (ListT m a)

runListT :: ListT m a -> m [a]

The inverse of ListT.

mapListT :: (m [a] -> n [b]) -> ListT m a -> ListT n b

Map between ListT computations.

• runListT (mapListT f m) = f (runListT m)

Lifting other operations

liftCallCC :: CallCC m [a] [b] -> CallCC (ListT m) a b

Lift a callCC operation to the new monad.

liftCatch :: Catch e m [a] -> Catch e (ListT m) a

Lift a catchE operation to the new monad.